app/views/layouts/_messages.html.erb
<% unless flash.empty? %>
<div class="margin-bottom-2">
<% flash.each do |name, msg| %>
<% if msg.is_a?(String) %>
<% alert_name = name == 'notice' ? 'info' : name %>
<div class="usa-alert measure-3 usa-alert--<%= alert_name %>" >
<div class="usa-alert__body">
<p class="usa-alert__text"><%= sanitize(msg) %></p>
</div>
</div>
<% end %>
<% end %>
</div>
<% end %>